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red lead,bright red to orange-red powder, also called minium, that is used in the manufacture of storage batteries, lead glass, and red pigments; a paint made with red lead is commonly used to protect iron and steel from rusting. Chemically, red lead is lead tetroxide, Pb3O4, a water-insoluble compound that is prepared by the oxidation of metallic lead or of litharge (lead monoxide); the commercial product sometimes contains litharge as an impurity.
Commonly used as a rust-inhibiting primer on steel, but has been largely superseded by other primers due to the toxicity of lead.
red lead[′red ′led]
A lead compound, lead tetroxide; bright red to orange-red in color; used in corrosion-resistant paints as a rust inhibitor on iron and steel.
a bright-red poisonous insoluble oxide of lead usually obtained as a powder by heating litharge in air. It is used as a pigment in paints. Formula: Pb3O4